Going Caveman: Will Crossfit Training, a Paleo Diet, and Minimalist Running Make You Prehistoric-Strong—Or Just Worn Out?

FRIDAY, MARCH 8: The Filthy 50.

It's one of CrossFit's hardest workouts: 50 reps of 10 different exercises, as fast as possible.

"You can pace yourself if you like," says trainer Mark Landis. "The pace is 100 percent all the time."

It starts with box jumps (just what they sound like—jump flat-footed from the floor onto the top of a two-foot-tall box, then jump back down) and continues with pull-ups, kettlebell swings, walking lunges, knees-to-elbows (hang from a pull-up bar and lift your knees up to your elbows, or as close as you can get them), a barbell press, back extensions, wall-ball shots (from a squatting position, throw a 20-pound ball high up against a wall, catch, repeat), burpees (drop into a push-up position, push yourself back up into a squat, then jump upright, repeat), and then a concluding session of jumping rope.

Halfway through the burpees, I'm sitting against the wall, arms wrapped around my legs, covered in sweat, dizzy and nauseated, my lungs scorched, muscles all over my body burning. I got through the first half in 13 minutes and thought I might actually get a respectable time.

I was wrong.

I turned 40 last year. I'm slightly overweight. I've been an off-and-on recreational runner for more than 20 years, a frequent hiker and occasional backpacker for almost as long, and for the last couple of years I've played rec-league soccer on weekends. I'm fit. But I'm not CrossFit. So I've signed up for a month of workouts to see what will happen. It's not starting well.

Thirty minutes is considered a pretty good time for the Filthy 50; 20 minutes or under is excellent. A few freaks have finished it in under 15 minutes. For me, though, time doesn't matter.

The digital timer on the wall ticks past 50 minutes. The rest of my class has finished, and the next group is starting to gather. My brain's a little mushy, but it finally occurs to me that I'm not going to finish this. In fact, I've already quit. I didn't make the decision; my body made it for me.

I walk over to the whiteboard where the day's participants have marked their names and times. They range from 18 minutes to more than 40 minutes. But they've all completed the workout.

I add my name in blue magic marker and the letters "DNF": Did Not Finish.


CrossFit, the newly super-popular exercise program, was founded in 2000 by Gary Glassman, an ex-gymnast who wanted to promote a real-world program that emphasizes overall fitness instead of just strength or endurance. There are now more than 4,000 licensed CrossFit gyms—or "boxes," as CrossFitters refer to them—around the world, with more than 10 million participants.

Landis, a trainer for 20 years, has been using the ideas that underpin CrossFit for about five years. In 2011, he purchased an official CrossFit license and opened CrossFit HTK ("Hard to Kill"), Knoxville's fourth box. HTK is located in the back of a grungy warehouse on Dutch Valley Road near Fountain City. A small sign at the entrance to the bombed-out gravel parking lot reads "GET ACTION MOVIE RIPPED!".

The lot in front of HTK is lined with orange cones to mark off distances for sprints. The space inside is dark and spartan—a huge metal door slides up to reveal a concrete floor and an imposing 10-foot-tall metal apparatus that can be used for chin-ups, bench press, and barbell squats. The floor is littered with big hunks of metal—barbell plates, kettlebells, and dumbbells. There's no front desk, no sign-in sheet, no snack bar. A stack of wire cubbyholes serves as the locker room; the shower and changing room is a tiny one-person bathroom in the rear corner. The large whiteboard in the center of the longest wall is HTK's command center. It's here that Landis scrawls the workout of the day (or "WOD," in CrossFit vernacular), which could look like "SQUAT 3-3-5-5-5 VOL 3x12" or "CLEAN AND JERK (135#/95#) 30 REPS FOR TIME." There's a trash can near the board, just in case someone throws up.

Landis is a squat 41-year-old with dark eyes, ripped muscles, an apparently limitless supply of bandannas, and a motivational tattoo across his chest—a pair of scythes and an hourglass above a ribbon that reads "It's later than you think." Over the last 20 years, he's been a powerlifter, a Brazilian jiu-jitsu wrestler, a kettlebell instructor, and now a certified CrossFit instructor and box owner.

"What we do here is we make people harder, better, faster, and stronger," Landis says. "We make them fit for the real world. Here you're considered an athlete, whether you need to drop a hundred pounds or not. ... We make people healthier, we make them bigger, and we make them ready for real life. A lot of women and men I train have young kids. Kids are 30, 40 pounds, whatever—you've got to pick those kids up. I'm amazed at the personal trainers I see who treat people like invalids. They'll have them pick up five- and 10-pound pink color-coded Ken and Barbie dumbbells. These people are picking up their kids! Who hasn't helped their friends move, or had to move a refrigerator, or a couch, or a stove? That's the real world, and that's what we do here. We prepare people to be better out there. But we make it so hard in here that out there everything is easier."

CrossFit, with its emphasis on variety and practicality, is just one part of a broader fitness and health movement that promotes what can generally be referred to as a kind of neo-caveman lifestyle. The high-protein, low-carb paleo diet (or Mark Sisson's Primal Blueprint, or the Zone), supposedly based on how our evolutionary ancestors ate before agriculture, is another element. There's also barefoot or minimalist running, popularized by Christopher McDougall's 2010 book Born to Run, which argues that conventional cushioned running shoes don't prevent injuries and may in fact contribute to them, since our bodies have been perfectly designed by tens of thousands of years of natural selection to run long distances over grass and dirt.

All of it is based on the idea that modern humans are ill-adapted to the environment they have built around themselves—that we evolved to live like our hunter-gatherer ancestors did 100,000 years ago, and that our air-conditioned offices and hi-tech sneakers and processed foods aren't just numbing our souls but are actually killing us. Today's cavemen point to so-called lifestyle diseases—heart disease, diabetes, and even cancer—as evidence of modern life's lethality.

"I just think modern technology over the last 100 years has made people less healthy and more sedentary," says Jeff Chapman, a marathoner, trail runner, weightlifter, and former American Gladiator contestant who lives in Harriman. "Since automobiles have been invented—before that, people used to walk everywhere. Now our lives consist of sitting down in a car to drive to work, where we sit down at a desk, and then sit down in the car to go back home to sit down on the couch and watch TV. And then we think a 30-minute workout at the gym is going to counteract that? And most of our jobs aren't tough labor like it used to be, where you had to hunt your food or plow the fields or even build a house with your bare hands. We're less physical."

But getting back to our ancestral roots can be hard, and it's not without its own risks. CrossFit, the paleo diet, and minimalist running all carry significant caveats: CrossFit has been associated with a rare and potentially fatal condition called rhabdomyolysis, in which the muscle fibers broken down through hard workouts are released into the bloodstream, where they're toxic; a panel of experts ranked paleo last in a recent U.S. News and World Report survey of 29 popular diets; and the shoe manufacturer Vibram, whose Five Fingers models helped kick off the minimalist running trend, is facing a class-action lawsuit over its claims about the benefits of its shoes.

Despite those concerns, and despite a lack of rigorous scientific evidence to back any of it up, it's become the single biggest health and fitness trend of the last decade. Partisans defend this stuff with a fanatical zeal—just check out the forums on the website PaleoHacks or the comments section on any news story critical of CrossFit. But is this new devotion to caveman fitness a sign that it's here to stay, or will it pass like other, previous workout fads? Is the past the future of fitness, or will the paleo lifestyle be kicked back to the Stone Age?


I'm back at HTK. It's my ninth official CrossFit WOD. I've also been eating an approximately paleo diet. I've cheated, more times than I can list, but I've eaten a lot of salads, a lot of nuts, and a lot of meat. Breakfast has been a homemade smoothie, lunch a salad, dinner eggs and sweet potatoes and spinach. I've largely given up beer, cheese, and bread. My clothes fit differently. On weekends, I've gone for hour-long trail runs in my new minimalist shoes. After a prolonged bout of fatigue in the second week, I feel better than I have in years.

I'm not sure if I've gotten stronger, but I've gotten more confident at the box. The week before, I finished in the top two-thirds during one of the dreaded benchmark WODs that CrossFitters use to measure their progress—Kelly, a session of running, box jumps, and wall-ball shots. (Most of these benchmark workouts are named after women; an apocryphal story attributes this to founder Gary Glassman: "I thought that anything that left you flat on your back, looking up at the sky, asking ‘What just happened to me?' deserved a female's name.")

Tonight's WOD is another benchmark, this one named Grace: 30 reps of the clean and jerk for time. You pull a barbell from the floor up to your chin, then push it overhead, then repeat 29 times. The standard weight for men in the WOD is 135 pounds. I can't even get that up to my chin, so I drop to 95 pounds, the standard weight for women. I can get that up, but there's no way I'll be able to do it 30 times. I drop all the way down to 65 pounds. It's less than half the prescribed weight, but it's going to give me a hell of a workout.

"If you feel okay and you're walking around a couple of minutes after you're done, you're doing it wrong," Landis warns us. "When this is over, you should feel like you're crapping blood."

After three reps, I'm pretty sure I'm doing it right. At 10, I'm resting after every three reps. I get to 15 and face each rep with increasing dread. My quads are burning and my arms feel like goo. I'm sweating and breathing hard. When I get to 20, other people in the class are finishing up. I get to 25 and know I'm almost there. On 29, I barely get the bar above my head; Landis tells me that rep doesn't count.

Finally, I'm done. It took me seven minutes and 47 seconds. I'm the last in my class to finish, but I got it done. According to the whiteboard where we all list our times, I'm not even the slowest person of the day—somebody took 10 minutes to complete the workout. I'll take it.

"When you work with iron, you become iron," Landis tells me as I'm leaving.


As the paleo lifestyle—its most devoted practitioners refer to it as the "ancestral health community"—has become more popular, it's also come under more scrutiny. The most convincing and detailed criticisms have come from scientists, who tend to roll their eyes at the suggestion that we should try to live like our Stone Age ancestors. The debate reached fever pitch in March with the publication of Paleofantasy: What Evolution Really Tells Us About Sex, Diet, and How We Live, by Marlene Zuk, an evolutionary biologist at the University of Minnesota. An excerpt appeared on the website for The Chronicle of Higher Learning in February, and it's been the subject of high-profile reviews from The New York Times and Salon.com—and a source of controversy among today's cavemen. Zuk's main assertion, shared by most mainstream scientists, is that modern caveman life is based on fundamental misunderstandings about how our ancestors lived and how evolution works.

"Let me tell you what we were designed for," says Michael Zemel, a retired University of Tennessee nutrition scientist who now serves as chief scientific officer for the biotechnology company NuSirt Sciences. "We were designed, from an evolutionary perspective, to nourish ourselves and live long enough to reproduce and raise our young to the point where they could be self-sustaining, which, back in the day, would have been the teenage years. ... This notion of eating for what we were designed to do—our design is a moving target. The goal of science and medicine is to optimize what we do, including what we eat, to maximize our health span."

It's not that this stuff doesn't work—it does. If you want to lose weight fast and get ripped, combine high-intensity weight work and a high-protein, low-carb diet. If years of running on asphalt has pounded your knees and connective tissue to jelly, or if you want to adopt a different stride, wear a more minimalist shoe on the trails. But other approaches work, too, and the valuable insights of "ancestral health" have been embraced by some people with a cult-like fervor, even though much of it is based on "common sense" and simplistic deduction rather than scientific evidence: if strength work is important, cardio workouts must be bad (see Mark Sisson's concept of "chronic cardio"); if cavemen did it or ate it, it must be good (some modern cavemen fast regularly to mimic the feast-and-famine routines of Paleolithic hunter-gatherers and frequently donate blood, since our ancestors fell off cliffs and fought saber-toothed tigers, even though there's no indication either practice improves health); if cavemen didn't do it, it must be bad (some modern paleos object to eyeglasses).

At its most extreme, paleo has become an ideology—for many practitioners, strict adherence to the program matters more than the real-life results. They act as if Jane Fonda and Nike Air cushioning, instead of over-processed junk food and sedentary lifestyles, are to blame for America's obesity epidemic. Take, for instance, beans, which are excluded from the paleo diet simply because they weren't a regular part of human nutrition before agriculture. There's no evidence that beans are bad for most of us; there's no good nutritional reason not to eat them, unless you have particular gastrointestinal difficulties. In fact, legumes are a good, cheap, and sustainable food staple. They have been part of traditional diets for thousands of years—banning them from your diet is an arbitrary decision that's simply not based on nutritional science.

"For me to endorse a diet or a dietary concept, it has to have extraordinarily sound science, as opposed to these vague ideas of ‘this is what we evolved to do,' which is by and large a crock," Zemel says. "That doesn't mean I think it's a bad diet—please don't misunderstand. I think that many, many scientists in the United States over the last 35 to 40 years have pushed too hard on low-fat diets, and in doing so have pushed us into unhealthy high-carbohydrate diets. And I think that's a mistake. To the extent that a diet like the paleo diet pushed us back a little bit toward a lower-carbohydrate diet, I fully endorse that. In the area of nutrition, there are so many ideas that sound good, sound like they ought to be true, they've got logic behind them. But nutrition is a biomedical field. It is a science. We test hypotheses. We test ideas. Just because it sounds good doesn't mean it is good."


Just five minutes into the SEAL Extreme Challenge, after half a mile of crowded running, the course turns away from the trail and straight up the side of a hill. It's a 200-yard ascent up through mud, loose dirt, and exposed tree roots, steep enough that it's a scramble on all fours. The last part is up through a narrow chute that's nearly vertical. It would be impossible to walk up the hill, much less run it; it's a long, slow, grueling climb that incapacitates major muscle groups that I will desperately need in the next 90 minutes.

The SEAL Extreme Challenge is a three-and-a-half-mile trail run, obstacle course, and adventure race rolled into one, named after the Navy's elite special-ops division. The event has been held for several years at a private commercial campground in Cosby, Tenn., just outside the Great Smoky Mountains National Park. I've selected it as the final test of my month of caveman living; it seems to have been a fitting decision, since more than half of the 200 entrants look to be fellow CrossFitters, many of them participating in four-person teams. It's a beautiful, crisp morning. The sun is already out by the 10 a.m. start, dissipating the slight morning chill.

Because of the crowd, it takes 10 or 15 minutes to get to the top of that first big hill, and then the trail drops into a steep, winding, quad-crushing descent; there's no rest, since I have to expend so much energy just to keep from tumbling out of control. The course eventually rounds back to the campground, where it started; there I face a walk, on already quivering legs, across an elevated log, a crawl under foot-high ropes, and a slog through a pit of cold, muddy, waist-high water. Then it's back into the woods at a slow trot, up and over a couple of climbing walls, up and down hilly trails, through another, bigger water pit.

Eventually everything hurts—my muscles are spent, my legs and hands are scraped and bruised, my lungs are raw. I'm covered in mud and sweat. I've got dried snot caked on my face—my nose is running from the intense, protracted exertion. I'm walking up hills now, and running when I can, which isn't often. I've been at it for nearly an hour; I figure I'm more than halfway done. There's a steep, unchecked slide—everything here is steep—down a bank of slippery mud and through a tangle of briars. I get up from the slide and almost immediately find myself once again at the bottom of the same hill I'd climbed an hour earlier.

I wasn't quite expecting that. It seems like an especially cruel, even sadistic feature of an already fiendish course. It doesn't occur to me to quit—I'm too close to the end, and I don't even know how I would get from where I am back to my car, anyway. But I really don't want to do this. I feel the same knot of dark dread in my gut that I felt during the Filthy 50.

I'm still not sure how I made it back to the top. My brain was on autopilot; I just put my nose in the dirt and moved. At one point a rock came sliding past me, kicked loose by another climber. I look back and marvel at just how steep it is. It takes 10 or 15 minutes to reach the top, but from there it's all downhill—not an easy descent, but an improvement over that climb. I pass a handful of other racers on the way down, confident that a few minutes and some mud is all that's left. That's nothing after what I've been through for the last month.